Sun visors for automotive vehicles conventionally employ adjustment screws for tightning visor and arm connections so that the visor will remain stored in raised condition against weight and vibration as well as at any desired angular position during use.
In some cases spring detent provisions have been employed in combination with flats on the visor arm, without adjusting means, to retain the visor in raised stored position, combined with frictional tubes along the pivotal edge of the visor for engaging the cylindrical mounting rod arm. Such frictional tubes have been formed with interference fits designed to provide adequate torque reaction for holding the visor in any angular adjusted use position and attempts have been made to provide limited spring characteristics and accurately size the inner tube dimension to assure consistency and durability of desired retention characteristics.
Such detent and supplemental frictional means have not been entirely satisfactory in several respects, as where double opposed flat detent springs engage opposed rod flats resulting in two detent positions 180.degree. apart. Snap action to an undesired position 180.degree. from storage has sometimes been encountered during use leading to sudden sun glare; and material variations in visor edge tubing, including heat treatment affecting spring quality, has led to undependable frictional characteristics in retaining adjusted visor position over the life of the car. Certain attempts have been made to employ opposed flat leaf springs, riveted to each other through an intermediate fiberboard core with free spring ends engaging the rod arm at respective longitudinally spaced locations with only one spring end aligned with a single flat thereby limiting the detent action to a single stored position of the visor. However, the holding power in stored position has been found to be inadequate or undependable since a flat spring with adequate thickness for sufficient torque resistance when engaging a single flat involves critical dimensions and compressive preload stress on the assembly rivets and a loss of adequate torque resistance under fatigue testing.